This invention relates generally to fire protection systems and, more particularly, to fire protection systems in which a plurality of individual fire suppressor units are simultaneously activated to extinguish a fire.
Certain fire protection systems employ a plurality of strategically located suppressor units, each including an extenguishant filled vessel and an electrical current operated explosive squib for inducing discharge of the extinguishant in response to detection of a fire. Normally the squibs are connected in a series string since a higher power density at each squib can be achieved in a series connection, than can be achieved in a parallel connection. In such systems, it is common technique to electrically supervise the electric integrity of the release squibs by providing and monitoring a trickle current through the series connection thereof. Although this series supervision establishes a constant knowledge of release mechanism integrity, there remains the possibility that a single release member failure will cause failure of the entire series system. In addition, even a detected failure of a release mechanism can prevent system operation if the detected failure occurs coincidentally with a demand for system actuation. Also, a fast-acting squib may cut off the current before a slower acting squib has had a chance to activate.
Solution to this problem is provided in U.S. Pat. Nos. 3,917,001 and 3,952,809. The systems disclosed in these patents include a circuit for switching the release squibs from a series to a parallel arrangement a short period after system activation is initiated. Although a substantial improvement over the prior art, the disclosed systems fail to detect and act on a fault condition prior to the detection of a fire condition.
The object of this invention, therefore, is to provide a more reliable fire protection system of the type employing a plurality of individual suppressant units all having electrically operated release mechanisms adapted for coincident activation.